1. Field of the Invention
The present invention relates to a Group III nitride semiconductor laser device, and a method for fabricating the Group III nitride semiconductor laser device.
2. Related Background Art
Patent Literature 1 describes a nitride semiconductor laser. In this nitride semiconductor laser, an active layer is formed on a (11-22) plane. (1-100) planes perpendicular to the (11-22) plane are used as end faces of a cavity to prevent reduction of luminous efficiency due to piezoelectric polarization and also to facilitate fabrication of the laser cavity. This configuration allows the fabrication of the semiconductor laser of a low threshold current with an excellent yield.
Non Patent Literature 1 describes a laser diode. This laser is fabricated on a (11-22) plane of GaN with the off-axis angle of 58 degrees, and the end faces of the cavity are formed by dry etching (RIE). Non Patent Literature 2 describes a laser diode. This laser is fabricated on a (20-21) plane of GaN with the off-axis angle of 75 degrees, and the end faces of the cavity are formed by dry etching (RIE). Non Patent Literature 3 describes a laser diode. This laser is fabricated on a (30-31) plane of GaN with the off-axis angle of 80 degrees, and the end faces of the cavity are formed by dry etching (RIE).    Patent Literature 1: Japanese Patent Application Laid-open No. 2006-128661    Patent Literature 2: Japanese Patent No. 4475357    Non Patent Literature 1: Hirokuni Asamizu, Makoto Saito, Kenji Fujito, James S. Speck, Steven P. DenBaars, and Shuji Nakamura, “Demonstration of 426 nm InGaN/GaN Laser Diodes Fabricated on Free-Standing Semipolar (11-22) Gallium Nitride Substrates,” Applied Physics Express 1 (2008) 091102    Non Patent Literature 2: Anurag Tyagi, Robert M. Farrell, Kathryn M. Kelchner, Chia-Yen Huang, Po Shan Hsu, Daniel A. Haeger, Matthew T. Hardy, Casey Holder, Kenji Fujito, Daniel A. Cohen, Hiroaki Ohta, James S. Speck, Steven P. DenBaars, and Shuji Nakamura, “AlGaN-Cladding Free Green Semipolar GaN Based Laser Diode with a Lasing Wavelength of 506.4 nm,” Applied Physics Express 3 (2010) 011002    Non Patent Literature 3: “InGaN/GaN Blue Laser Diode Grown on Semipolar (30-31) Free-Standing GaN Substrates,” Po Shan Hsu, Kathryn M. Kelchner, Anurag Tyagi, Robert M. Farrell, Daniel A. Haeger, Kenji Fujito, Hiroaki Ohta, Steven P. DenBaars, James S. Speck, and Shuji Nakamura, Applied Physics Express 3 (2010) 052702